What Is a Slugline? Scene Headings Explained

October 24, 2026 • By Greenlight Writing

A slugline, also called a scene heading, is the line at the top of every scene that tells the reader where the scene happens and when it happens. It is written in uppercase, on one line, and it always comes before the action. If you can read a slugline, you can place yourself in the scene before a single character speaks.

A standard slugline has three parts, in this order: interior or exterior, location, and time of day. Interior is shortened to INT. and exterior is shortened to EXT. A simple example reads INT. COFFEE SHOP-DAY. That one line says the camera is inside, the place is a coffee shop, and it is daytime. Nothing else is needed, and nothing else belongs there.

The three parts, in order

1. Interior or exterior

INT. means the scene plays inside something: a room, a building, a car, a spaceship. EXT. means the scene plays outside, in open air. The choice is about camera placement, not about whether the location has a roof in real life. A scene shot on a studio backlot street can still be EXT. if the camera is outside, and a scene inside a car is INT. even though the car is outdoors.

When the action moves between inside and outside without a cut, for example a conversation through an open window or a scene in a moving car, writers use INT./EXT. That combined form tells the reader the scene will cross the boundary, so no one has to guess where the camera is.

2. Location

The location is a place, named plainly. COFFEE SHOP, KITCHEN, ROOFTOP, HIGH SCHOOL HALLWAY. It should be specific enough that a reader can picture it and a production team can plan it, but short enough to read at a glance. A location is not a mood, a date, or a description. A heading that reads like a summary of the scene has already failed, because the reader is left asking where they actually are.

Be specific where specificity helps the story. If the scene needs a particular room, name it. INT. MAYA'S APARTMENT-KITCHEN-NIGHT puts the reader in the kitchen, not just somewhere in the apartment. If the room does not matter, do not invent one. A vague heading wastes the reader's trust, and a needlessly long heading slows the read for no gain.

3. Time of day

Time of day is usually DAY or NIGHT. Writers also use MORNING, EVENING, DAWN, DUSK, and CONTINUOUS when the scene follows directly from the previous scene without a time jump. LATER and MOMENTS LATER mark a short gap in the same place. The point is orientation, not precision. A heading that tries to pin down an exact clock time usually belongs in the action, if it belongs anywhere at all, because a production schedules scenes by day and night, not by the minute.

Master headings and secondary headings

The heading that opens a scene is a master scene heading. It names the master location, the primary place where the scene happens. Once that master location is established, a writer can move within it using a secondary heading, sometimes called a mini slug.

Take a house as the master location. The master heading might read INT. MAYA'S HOUSE-NIGHT. The action can then move to another room with a short secondary heading in uppercase, such as KITCHEN or HALLWAY, without repeating the full heading. The reader stays inside the same house, so no new master heading is needed.

The rule is simple: a secondary heading only works inside the master location you already established. The moment the action leaves that location, or the camera placement changes from interior to exterior, you need a new master heading. Jumping from a swamp to a bathroom with only a one word heading in between is the classic version of this mistake, and it confuses readers because the geography no longer adds up.

When to write a new slugline

Write a new slugline whenever the location changes, whenever the time changes, or whenever both change. Every scene gets its own heading, and a script with fifty scenes has fifty master headings. That count is not a flaw. It is the structure a reader, a director, and a scheduler all rely on to find their way through the script.

A few situations deserve care. If two scenes play back to back in the same location with time passing between them, add a time marker such as LATER to the heading rather than leaving the reader to assume nothing changed. If a sequence moves continuously through several places, for example a chase through city streets, keep one broad master location and use secondary headings for the stops along the way, then write a new master heading when the sequence leaves that area. If a scene returns to a location hours later, that is a new scene, and it earns a new heading with the new time.

What sluglines do for production

Sluglines are not decoration. They are the unit a production breaks a script down by. From the headings alone, a production team can count locations, count day scenes against night scenes, group scenes that shoot in the same place, and build a schedule. A heading that is vague or inconsistent makes that work harder, and a heading that is wrong, for example an interior heading for a scene that clearly plays outdoors, creates real scheduling problems later.

That is also why sluglines matter to a first reader. A reader who can always answer the question "where am I, and when is it" stays inside the story. A reader who has to stop and reconstruct the geography has already left it. Clean headings are a quiet form of respect for the reader's attention, and they signal that the writer understands the script as a production document, not just as prose.

Common slugline mistakes

• A location that is not a location. A mood, a holiday, or an event is not a place. Name the place first, and let the action carry the mood.
• Jumping between interior and exterior without a new heading. If the camera moves from outside a house to inside it, write the new heading. Do not expect a one word heading to do that work.
• Overstuffing the heading. Every extra place name, direction, and detail in the heading is a detail the reader must hold before the scene starts. Keep it to the place and the time, and put the rest in the action.
• Lowercase or mixed case headings. Scene headings are uppercase, always. A lowercase heading looks like an action line, and the reader will read it as one.
• Camera directions inside the heading. The heading says where and when. Staging belongs to the director, and camera language on the page is a separate problem.
• Scene numbers on a submission script. Numbered scenes belong to a shooting script in production. A script being read for its story does not need them, and they mark the draft as premature.
• A new heading for every camera angle. A change of angle inside one continuous scene is not a new scene. Use a secondary heading or let the action carry the movement.

How sluglines fit the rest of the page

A slugline is followed by action, then by character cues and dialogue as the scene plays out. Our guide to how to format a screenplay walks through all six screenplay elements and where each one sits on the page, and it is the natural next read after this one. The heading sets the scene, the action shows what happens in it, and the dialogue gives the scene its voice. None of the three can do the others' job.

The format is also the reason a writing tool matters. Almost no one holds these measurements by hand. GREENLIGHT Create shows the writer the true US Letter page while typing, with the heading at the margin in uppercase and dialogue in its narrow block, so the format a reader will judge is the format the writer sees. The GREENLIGHT Academy teaches format as part of the craft, because a heading is the first production decision a writer makes, not an afterthought applied at the end.

When the script is ready to leave your hands, the same discipline continues. Protect Your Work covers what to do before the script goes out, and Discover lays out how a finished script reaches readers on the industry side. A clean heading will not sell a weak story, but a messy one can slow a strong story down before it gets a fair read.

Frequently asked questions

Is a slugline the same thing as a scene heading?

Yes. Slugline is the common nickname, and scene heading is the formal term used by screenwriting software. They mean the same line at the top of a scene.

Can a slugline be more than one line?

A master heading is one line. A heading that spills onto a second line is usually trying to carry too much information. Shorten the location, and move the extra detail into the action.

What if my scene has no clear time of day?

Use DAY or NIGHT, and let the action establish anything more specific. A heading needs a time slot a production can schedule, not a poetic description of light.

Do I need a slugline for a dream, a flashback, or a montage?

Yes, with the same three parts. If the sequence needs a label, it goes in the action or as part of the location description in a way that stays readable, not as a replacement for the place and the time. A dream still happens somewhere, and the reader still needs to know where.

How do I know my sluglines are working?

Read only the headings, top to bottom, without the action. If you can follow the geography and the time of the whole story from the headings alone, they are working. If you hit a heading and cannot say where you are, rewrite that heading before you rewrite anything else.

Sources

• Screenplay Formatting and Elements, Final Draft
• What Is a Slug Line? How to Write Scene Headings in a Screenplay, Backstage
• Both sources were read on October 24, 2026. The guidance above follows the points those sources agree on: a heading is one uppercase line carrying interior or exterior, location, and time of day, with master headings opening scenes and secondary headings moving within an established location.